App Note:
Expand Input Capability Using Binary Codes
Increase Your I/O The Exponential Way
In many complex show designs, external subsystems (such as a Ride Control PLC) must provide the Show Control system with detailed status information in a timely manner. While this can be readily accomplished by taking advantage of discrete inputs to trigger individual sequences within the show controller, even a modest amount of outputs from the PLC can quickly overtake input capacity. This application note demonstrates how to use binary coding to greatly increase the number of discrete sequence triggers available to a single device, while maintaining adequate input connections for show control use.

The diagram below shows a V16+ interposed between a ride control system and audio video playback equipment. The A/V equipment has the ability to play back hundreds of clips, and the ride control system could certainly have hundreds of buttons or sensors. The question is: how do we get the ride control system to tell the V16 what button was pushed without doing a bunch of (painful) programming in the PLC?

The simple answer is: use a strobe and binary coded bits. If a single parallel line from the PLC triggers a sequence in the V16, this sequence can easily examine the contents of other bits (in this example, seven of them) and play back audio or video based upon their configuration. Using a strobe and seven bits give you 2 to the seventh possible combinations, or 128 different commands that may be issued.

Of course, this technique can be used for more than A/V playback. Any time a large number of messages need to be sent from a simple device, it's worth considering using binary encoded bits and a strobe.

Show Control V16+
System Diagram

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